Fibrillation



0 1969 H. D. BOULTINGHOUSE 3, 7

FIBRILLATION Filed Dec.

INVENTOR.

H. D. BOULTENGHOUS:

ye '54 (Q5 A T TORNEYS nited States Patent 6 US. Cl. 28-72 5 Claims ABSTRACT OF THE DISCLOSURE Partially fibrillated. staple is further fibrillated and bulked by tumbling the staple in a confined zone with a vaporous stream.

This invention relates to new and improved method for fibrillating a fibrillatable film. This invention also relates to a new and improved method for bulking a fibrillated film.

Heretofore, molecularly oriented polymeric films have been fibrillated by various methods. A full and complete disclosure of one suitable method for fibrillating a molecularly oriented polymeric film and the fibrillated product can be found in US. Patent 3,302,501, issued Feb. 7, 1967. Generally, fibrillation processes produce a product which can then be bulked by any conventional method to give the product the feel desired by the consumer. Sometimes, the additional bulking step can cause additional fibrillation of the product, thereby causing the final bulked product to be fibrillated to degree greater than that desired, i.e., contain smaller diameter fibers than desired.

According to this invention, a fibrillated product is obtained which has both the desired degree of fibrillation and the desired bulking, without excessive fibrillation, by exposing partially fibrillated polymeric film staple in a confined zone to a vaporous stream under pressure, the stream being injected into the confined zone at an angle to the major direction of passage of that tream through the confined zone so that the staple is tumbled in the confined zone, thereby causing further fibrillation and bulking of the staple. By adjusting the pressure of the vaporous stream injected into the confined zone, the path of that stream in the confined zone, the residence time of the staple in the confined zone, and the like, the desired degree of fibrillation is obtained at the same time that the bulking operation takes place. The staple can thereby be fibrillated and bulked at the same time, thus obviating the risk of over fibrillating the staple by subjecting the fibrillated staple to a separate bulking step.

The fibrillated product of this invention is useful in making car-pet backing, insulation, filtering mediums, and the like.

It is an object of this invention to provide a new and improved fibrillation method. It is another object of this invention to provide a new and improved bulking method. It is another object of this invention to provide a new and improved method to obtain the desired degree of fibrillation while bulking a fibrillatable product. It is another object of this invention to provide a new and improved method for obtaining the desired bulked product without over fibrillating same.

Other aspects, objects, and the several advantages of this invention will be apparent to those skilled in the art from the description, drawings, and appended claims.

The drawing shows apparatus useful in the practice of the method of this invention.

In the drawing, there is shown a confined cylindrical zone 1, the upper end of which is closed by a wire screen 2. Bottom 3, as well as the circular side of zone 1 are not necessarily porous so that a vaporous stream injected into the interior of zone 1 through orifice 4 exits primarily through screened end 2. A fluid stream is injected into the interior of zone 1 by way of jet 5, the fiow of vapor through jet 5 being controlled by conventional needle valve 6.

The vapor injected into zone 1 through orifice 4 therefore has a major direction of passage substantially parallel to arrow 7 before exiting through screened end 2. Vapor is injected into cylinder 1 at an angle to the major direction of passage of the vapor tream through zone 1, i.e., at an angle to the direction of arrow 7, so that the vapor passes circuitously, e.g., spirally, through the interior of cylinder 1 before exiting through screened end 2. This circuitous path of travel of the vapor spins and/or tumbles the staple causing the staple to bend, twist, and collide with other staple as well as the walls of zone 1, thereby further fibrillating the staple and also bulking the staple so that it has a feel considered desirable by the consumer.

Generally, any orientable polymeric film can be employed in this invention. The film can be uniaxially molecularly oriented, or multiaxially molecularly oriented if this condition allows fibrillation. The film can be molecularly oriented in any conventional manner known in the art including super cooling the film and then orienting same by stretching and the like, or heating the film to a temperature below that at which the film is in the molten state and then stretching same. By molecular orientation, what is generally meant is deforming, e.g., stretching the film below that temperature at which the filrn is substantially in the molten state, to thereby increase the strength of the film at least in the direction in which it is plastically deformed.

Generally, films of mono-l-olefins having from 2-8 carbon atoms per molecule which have been oriented by stretching in at least one direction so that the film after stretching is at least three times longer in the direction of stretching than it was before stretching, i.e., a draw ratio of 3:1, can be used. When film of polyethylene which has a density of at least about 0.94 grams per cubic centimeter is employed, the draw ratio should be at least 4:1 and when polypropylene is employed, this draw ratio should be at least 6: 1. Polymers of l-olefins can be made in any conventional manner, a particularly suitable method being that which is disclosed in US. Patent 2,853,741. The film can be made from the polymers in any conventional manner such as by extrusion, casting, flattening, blown tubing, and the like, and thereafter cutting the staple length. Staple length is substantially any finite width and length, but generally is of a length of from about 1 to about 12 inches and a Width of from about A; to about 12 inches.

Other conventional and fibrillatable plastic films can be employed in this invention including blends and copolymers of l-olefins as above described with each other and with other polymers such as polyamide, polyester, polyvinyl alcohol, acrylic polymer, polyvinylchloride, polyvinylacetate, polyvinylidenechloride, and the like. Homopolymers of l-olefins and other materials described can be employed as well as copolymers or blends of two or more homopolymers and/ or copolymers. A draw ratio of at least 3:1 can also be employed with these other plastic films.

The staple thickness can vary Widely, the minimum thickness being that which will produce a substantially self-sustaining film, with a maximum thickness being dictated by the apparatus employed, and the degree of fibrillation and bulking desired. The thickness of the staple will generally vary from that which is suflicient to form a self-sustaining film to about 6 mils.

The vapor employed in the confined zone {zone 1 of the drawing) can be any suitable material which is substantially nondeleterious to the staple with which it is to contact. Generally, any gaseous medium can be employed such as steam, air, nitrogen, argon, helium, and the like. The vapor is employed under a pressure which can vary widely but will generally be at least p.s.i.a. The vapor can be injected into the confined zone at an angle of at least five degrees away from the major direction of passage of the vapor through the zone, i.e., at least five degrees away from the direction of arrow 7 of the drawing, and is preferably directed at an angle of at least five degrees from the side of the confined zone to thereby give a spinning trajectory to the vapor as it leaves jet 5.

The staple can be partially fibrillated using any known fibrillation method. Known fibrillation methods include those disclosed in US. Patent 3,302,501, and US. Patent 3,003,304, the disclosures of which are hereby incorporated herein by reference.

The process of this invention can be carried out using the bulk operation or continuously as desired.

EXAMPLE A homopolymer of propylene having a melt flow of 4 (ASTM D123862T) was converted into 2 mil thick tubular blown film with a layfiat width of 14 inches. The flatened tube was molecularly oriented at a draw ratio of 14:1 to give a double layer 4%" wide product with a nominal single wall thickness of 0.6 mil. The oriented product was subsequently partially fibrillated and crimped by passage through a conventional stuffer box crimper and the resulting material was cut into staple about to /2" long.

Five pounds of the staple was then placed in the apparatus shown in the drawing, zone 1 having a diameter of 18 inches and a height of 58 inches. A 4 inch inside diameter nipple was used for the jet 5 and air under a pressure of 100 p.s.i.g. was admitted into the interior of the zone 1 thereby. Jet 5 was oriented in zone 1 as shown in the drawing, i.e., angled upwardly and to the right to achieve a spiral route for the air stream as it passed through zone 1 and excited therefrom through screened end 2. After 5 minutes of introducing air into zone 1 at substantially room temperature. The run was terminated and the staple in zone 1 removed and examined.

The staple was found to have been fibrillated to a greater extent than when originally placed in zone 1 and 4 to have additionally been bulked since it gave a more bulky feel to the hand than when originally placed in zone 1.

Reasonable variations and modifications are possible within the scope of this disclosure without departing from departing from the spirit and scope thereof.

I claim:

1. A method comprising providing a confined zone containing partially fibrillated polymeric film staple, and injecting into said zone a vaporous stream under pressure, said stream being injected into said zone at an angle to the major direction of passage of said stream through said zone so that said passes circuitously through said zone the force of said stream being such to tumble said staple within said confined zone thereby causing said staple to be further fibrillated and to be bulked.

2. The method according to claim 1 wherein said staple is first crimped, the staple length is from about one to about 12 inches, and the staple width is from about A; to about 12 inches.

3. The method according to claim 1 wherein said staple is formed of materials selected from the group consisting of homopolymers of l-olefins having from 2-8 carbon atoms per molecule, inclusive copolymers of two or more of said l-olefins, polyamides, polyesters, polyvinylalcohol, acrylic polymers, polyvinylchloride, polyvinylacetate, polyvinylidenechloride, and mixtures thereof.

4. The method according to claim 1 wherein said stream is under a pressure of at least 5 p.s.i.a. when introduced into said confined zone.

5. The method according to claim 1 wherein said staple is formed of materials selected from the group consisting of homopolymer of ethylene, homopolymer of propylene, and copolymer of at least two of ethylene, propylene, and =butene-1, said stream is air, and said stream passes spirally through said zone.

References Cited UNITED STATES PATENTS 3,336,174 8/1967 Dyer et al. 3,378,997 4/1968 Matsui et al. 28-1 X LOUIS K. RIM-RODT, Primary Examiner US. Cl. X.R. 281

Disclaimer and Dedication 3,473,206.Har0ld D. Boulti'nghouse Bartlesville, Okla. FIBRILLATION. Patent dated Oct. 21 1969. bisclaimer and dedication filed Dec. 28, 1971, by the assignee, ihillips Petroleum Gomynany. Hereby disclaims said patent and dedicates to the Public the remaining term of said patent.

[Oficial Gazette April 11, 1.972.] 

